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Is Tens the same as NMES?

I use digistim NMES for pelvic floor rehab, settings usually 35 hz and 250 us intravaginally to elicit a motor response, contraction time between 2-10 seconds, relaxation time between 4-20 seconds, depending on the patient.

I don't understand the difference between a digistim and a TENS for pain relief - if they are both set at the same Hz and Us. Yet i think there is a difference?

If i tried to use a Tens i have a feeling it would not elicit a contraction, but can't figure out why.
thanks

Hi Clare,
My understanding has always been ( and please anyone correct me on any of this) :
They all cause neuromodulation , but how depends on the parameters.
When using TENS for OAB via tibial nerve the parameters ( mainly Hz) are quite different to when you use NMES for muscle contraction. It is also used on continuous mode as compared to a work/rest function which is really the simplest way of explaining the difference.
Most research uses 10Hz for OAB although some goes up to 20 Hz ,
You won't get a tetanic contraction at 10 Hz , rather a flickering, but the idea is to take the mA up until you get twitching to ensure you have you electrode placement correct ( over tibial nerve) then turn down the mA until current is comfortable but not causing contraction. If you put the electrodes on yourself and play with the Hz you will feel (and see) the difference in contraction quality. Also with lower Hz you tend to get more of a sensory effect ( which you want with OAB ) but will get motor if mA is high enough. When you stim the pelvic floor for contraction you are using the higher Hz as you say and that is what gives a tetanic contraction ( up to a point , past about 50Hz there is no time for depolarisation so contraction drops off and you get more of a sensory effect again.) Plus you are using a work/rest parameter as you don't want a continuous contraction!
The pulse width general rule is wider it is the deeper it goes and can be adjusted for comfort but the wider pulse is less comfortable.
I think too many people just use the pre-set programs on the machines without having a play with the parameters via the custom programs to individualise them for the patient and when the preset doesn't work they give up saying stim/TENS doesn't work.
I also think as physios we tend to use TENS and E-stim as a 'last resort' when we should be employing them much earlier in pelvic floor rehab in particular ...but that is my little soapbox!

I see your point. Most of the published work in this application does use a TENS device and is aiming for sensory level effect rather than a motor one. I was looking through the literature again the other day as someone who was doing a PhD on this topic had e mailed me a similar question. Some people are certainly using an NMES type stimulator - but most of what I hear about is anecdotal rather than 'published' as such. The recent paper by Janssen et al [Janssen, D. A., et al. (2017). "Clinical utility of neurostimulation devices in the treatment of overactive bladder: current perspectives." Med Devices (Auckl) 10: 109-122.] might be of interest to you - though it is comparing TENS with sacral nerve root stimulation and sacral anterior root stimuation. I would suggest, in response to your final comment, that both TENS and NMES should have an effect with this patient group. My personal understanding f the literature is that TENS is the more strongly evidenced. Any help? Tim

Thank you Prof Watson.
That has helped.
My query stemmed from the use of TENS for overactive bladder over the posterior tibial nerve.
The research i have looked at refers to the use of TENS for OAB, but i know some use NMES to try and gain a contraction of extensor hallucis. (the type of unit i would traditionally use for strengthening pelvic floor muscle).
I have considered using TENS over the nerve, but was questioning whether i should be using a NMES unit and trying to gain a motor effect.
So if i use 10 Hz and 250 us parameters - either unit will give a similar response?

Clare. Thanks for your query. Both NMES and TENS are pulsed currents and they are pretty similar in terms of the basic stim parameters. Generally, as Cliff says, the TENS devices employ shorter duration pulses (the microsec parameter in the tech specification) and the NMES devices will tend to use longer pulse durations. Neither can be exclusive to sensory or motor nerve effect - it is entirely possible for a TENS device to generate a motor effect and for an NMES device to have a sensory component - can not entirely separate them out - BUT the NMES effect will be motor dominant and the TENS sensory dominant. One would normally select the stim parameters to have the optimal - i.e. most efficient outcome depending on whether you aim to have a predominantly motor or sensory result. Think of it this way - they are BOTH nerve stimulators - and therefore their effects must be similar - it is a matter of which nerve type is the dominant one that is responding ??? any help ????

HI Cliff and Niki,
thanks for getting back to me so quickly.
The reason i am asking is that i am looking at using tens over the posterior tibial nerve for overactive bladder treatment.
But am slightly confused as some report that when using stimulating the nerve, you may get an activation of extensor hallucis which if it were Tens, you shouldn't get a muscle contraction.
That led me to ponder what the difference is between tens and nmes - and whether some use nmes to stimulate the posterior nerve rather than tens?
Is the 250 uS the pulse width that you were referring to Cliff?
And Nikki, i have read the waveform is different, do you know in what way at all?
By the way i have stumbled across this forum and am very excited about it.
its great!
Cheers

HI Cliff and Niki,
thanks for getting back to me so quickly.
The reason i am asking is that i am looking at using tens over the posterior tibial nerve for overactive bladder treatment.
But am slightly confused as some report that when using stimulating the nerve, you may get an activation of extensor hallucis which if it were Tens, you shouldn't get a muscle contraction.
That led me to ponder what the difference is between tens and nmes - and whether some use nmes to stimulate the posterior nerve rather than tens?
Is the 250 uS the pulse width that you were referring to Cliff?
And Nikki, i have read the waveform is different, do you know in what way at all?
By the way i have stumbled across this forum and am very excited about it.
its great!
Cheers

...is the base of ELECTROPHYSICAL AGENTS... TRANSCUTANEOUS NERV STIMULATION usually doesn't give a motor effect on the muscle (at high intensity and frequency can give it, works only on nerves, for the modulation of the pain.
Instead, the NEUROMUSCULAR ELECTRICAL STIMULATION is just for work on muscle contraction... the waveform is different, the duration of the stimulus is longer, the frequency is "different"...